This is a series of lecture notes on nonlinear dynamics for physicists. The level is that of an advanced undergraduate or beginning graduate student. The main aim of these lectures is to present a balance of qualitative and quantitative material. The book also aims to address three main questions about nonlinear dynamics: what is nonlinear dynamics all about and what makes it differ from linear dynamics which permeate all familiar textbooks?; from the physicist's point of view, why should we study nonlinear systems and leave the comfortable territory of linearity?; and how can one progress in the study of nonlinear systems both in the analysis of these systems when we know them, and in learning about new systems from observations of their experimental behaviour? As it would be impossible to answer these questions in the finest detail, this volume nevertheless points the way for the interested reader. Useful problems have also been incorporated as a guide.